1. Field of the Invention
The present invention relates to a method for the manufacture of an electronic device which has at least a patterned layer chosen from a patterned conductive metal layer, a patterned laminate member comprising a transparent conductive layer and a nontransparent or reflective conductive layer, and a patterned non-single-crystal semiconductor layer, such as a semiconductor photoelectric conversion device, field effect transistor, liquid crystal display or the like, and more particularly to improvements in an electronic device manufacturing method which includes at least a step of forming a layer member to be patterned, which is chosen from a conductive metal layer member, a laminate member comprising a transparent conductive layer and a nontransparent or reflective layer, and a non-single-crystal semiconductor layer member, and a step of patterning the layer member by means of one or more laser beams.
2. Description of the Prior Art
Heretofore there has been proposed an electronic device manufacturing method which includes at least a step of forming a layer member to be patterned, which layer member is chosen from a conductive metal layer member, a laminate member comprising a transparent conductive layer and a nontransparent or reflective layer, and a non-single-crystal semiconductor layer member, and a step of patterning the layer member by means of a laser beam to form a patterned layer including a patterned conductive metal layer, a patterned laminate member comprising a transparent conductive layer and a nontransparent or reflective conductive layer, or a patterned non-single-crystal semiconductor layer. Compared with another manufacturing method which employs a photolithography technique for the formation of such a patterned layer, the abovesaid method excels in that the patterned layer can be formed without any defects. The reason for this is that in the case of forming the patterned layer by photolithography, a photoresist mask used therein is prone to pinholing or exfoliation at its marginal edges, which results in the formation of defects, whereas the method utilizing the laser beam patterning process has no such factors which cause defects.
With the conventional method employing the laser beam technique for the formation of the patterned layer, it is a general practice to use a YAG laser which emits a laser beam having a relatively long wavelength of about 1060 nm.
The absorption coefficient of the layer member for a laser beam of such relatively long wavelength is extremely small. For example, when the layer member to be patterned is a conductive metal layer member constituted principally of a sublimable metal such as Cr, Cr-Cu alloy, Cr-Ag alloy or Cr-N alloy, or a nonsublimable metal such as Al, Cu, Ag, Ni, Mg or stainless steal, or when the laminate member comprises a transparent conductive layer constituted principally of a sublimable metallic oxide such as SnO.sub.2, In.sub.2 O.sub.3 or ITO (Indium-Tin oxide), a sublimable metallic nonoxide such as Si-Cr or Si-Ni alloy, or a sublimable metallic nitride such as SbN, InN or Sn.sub.5 N.sub.4, and the nontransparent or reflective conductive layer member is constituted principally of the abovesaid sublimable metal or the nonsublimable metal referred to above as the conductive metal layer member, or when the non-single-crystal semiconductor layer member consists principally of a sublimable semiconductor material such as Si, Si.sub.x Ge.sub.1-2 (0&lt;x&lt;0.5), Si.sub.x C.sub.1-x (0&lt;X&lt;1), Si.sub.3 N.sub.4-x ( 0&lt;x&lt;2) or SiO.sub.2-x (0&lt;x&lt;1), the absorption coefficient of the layer member to be patterned is 10.sup.2 /cm or less. The reason for this is as follows: In the case where the laser beam has a wavelength as long as 1060 nm, its optical energy is much smaller than the optical band gap energy of the layer member to be patterned. For instance, in the case of the laser beam having a wavelength of 1060 nm, its optical energy is about 1.23 eV. On the other hand, when the layer member is the abovesaid conductive metal layer member, the laminate member comprising transparent and nontransparent conductive layers, or a non-single-crystal semiconductor layer member, its optical band gap energy is in the range of 3 to 4 eV.
For patterning of the layer member by a laser beam having such a relatively long wavelength of 1060 nm or so, it is necesssary that the laser beam be high-powered, since the absorption coefficient for the laser beam of the layer member to be patterned is extremely small. And therefore, when the layer member to be patterned is as thin as 2 .mu.m or less, it is feared that the substrate and other layers underlying may be damaged or patterned. Also it is feared that the marginal edges of the patterned layer will become swollen or exfoliated.
Furthermore, in the case of the laser beam having such a relatively long wavelength of 1060 nm or so, it is difficult to reduce its minimum spot diameter to a small value of 100 .mu.m or less. Therefore, it is difficult, with the conventional manufacturing method, to finely form the patterned layer with high precision. In addition, in the case of simultaneously forming a plurality of patterned layers, they cannot be spaced apart a small distance of 100 .mu.m or less. This imposes severe limitations on the fabrication of a small and compact electronic device having the patterned layer.